1. Field of the Invention
The present invention relates to complexes of certain aromatic hydrocarbons and metal salts. More particularly, the present invention relates to liquid clathrates of small aromatic hydrocarbons and metal salts formed by the combination of an alkali metal, ammonium or the like nitrate with a trialkyl aluminum compound wherein the liquid clathrate is immiscible in the neat aromatic hydrocarbon.
2. Description of the Prior Art
Liquid clathrates of small ring aromatic compounds and complex metal salts formed by the reaction of simple alkali metal or ammonium salts with trimethylaluminum in a mole ratio of 1:2 are known as described in a series of publications authored by J. L. Atwood et al in the Journal of Organometallic Chemistry (Vol. 66, pp. 15 -21 (1974); Vol. 42, pp. C77 - 79 (1972); Vol. 61, pp. 43 - 48 (1973); and Vol. 65, pp. 145 - 154 (1974)). The complex metal salts which form the liquid clathrates with certain aromatic solvents are prepared by reacting simple salts such as the alkali metal or ammonium halides, azides, thiocyanates and selenocyanates with trimethylaluminum in appropriate amounts such that salts of the stoichiometry, M[Al.sub.2 (CH.sub.3).sub.6 X] are formed. When the complex metal salts are treated with certain aromatic compounds such as benzene or toluene, liquid complexes or clathrates form which contain at least two and up to about 13 aromatic molecules per complex salt molecule. The liquid clathrates can be distinguished from the rest of the particular aromatic hydrocarbon solvent to which the complex metal salt is exposed by the formation of a second liquid layer which is immiscible with the hydrocarbon solvent.
Despite the fact that the trimethylaluminum-simple salt complexes form liquid clathrates, no examples are known of complex salts containing trialkylaluminum moieties wherein the alkyl groups are greater than methyl, which form liquid clathrates. Furthermore, it would be desirable to possess complexes which form clathrates with more than 13 aromatic molecules per molecule of complex and which form clathrates with aromatic molecules such as naphthalene, anthracene, phenanthrene, and the like sizes greater than the simple aromatic molecules.
A need therefore, continues to exist for trialkylaluminum-simple complexes which form liquid clathrates with relatively large numbers of relatively large aromatic molecules.